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/*
    Copyright (C) 2014 Carl Hetherington <cth@carlh.net>

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include "local_time.h"
#include "exceptions.h"
#include <boost/lexical_cast.hpp>
#include <cstdio>

using std::string;
using boost::lexical_cast;
using namespace dcp;

LocalTime::LocalTime ()
{
	time_t now = time (0);
	struct tm* tm = localtime (&now);
	_year = tm->tm_year + 1900;
	_month = tm->tm_mon + 1;
	_day = tm->tm_mday + 1;
	_hour = tm->tm_hour;
	_minute = tm->tm_min;
	_second = tm->tm_sec;

	int offset = 0;
	
#ifdef LIBDCP_POSIX
	offset = tm->tm_gmtoff / 60;
#else
	TIME_ZONE_INFORMATION tz;
	GetTimeZoneInformation (&tz);
	offset = tz.Bias;
#endif

	bool const negative = offset < 0;
	offset = negative ? -offset : offset;

	_tz_hour = offset / 60;
	_tz_minute = offset % 60;

	if (negative) {
		_tz_hour = -_tz_hour;
	}
}

/** @param s A string of the form 2013-01-05T18:06:59+04:00 */
LocalTime::LocalTime (string s)
{
	/* 2013-01-05T18:06:59+04:00 */
        /* 0123456789012345678901234 */
	
	if (s.length() < 25) {
		throw TimeFormatError (s);
	}

	/* Check incidental characters */
	if (s[4] != '-' || s[7] != '-' || s[10] != 'T' || s[13] != ':' || s[16] != ':' || s[22] != ':') {
		throw TimeFormatError (s);
	}
	
	_year = lexical_cast<int> (s.substr (0, 4));
	_month = lexical_cast<int> (s.substr (5, 2));
	_day = lexical_cast<int> (s.substr (8, 2));
	_hour = lexical_cast<int> (s.substr (11, 2));
	_minute = lexical_cast<int> (s.substr (14, 2));
	_second = lexical_cast<int> (s.substr (17, 2));
	_tz_hour = lexical_cast<int> (s.substr (20, 2));
	_tz_minute = lexical_cast<int> (s.substr (23, 2));

	if (s[19] == '-') {
		_tz_hour = -_tz_hour;
	} else if (s[19] != '+') {
		throw TimeFormatError (s);
	}
}

string
LocalTime::as_string () const
{
	char buffer[32];
	snprintf (
		buffer, sizeof (buffer),
		"%04d-%02d-%02dT%02d:%02d:%02d%s%02d:%02d",
		_year, _month, _day, _hour, _minute, _second, (_tz_hour >= 0 ? "+" : "-"), abs (_tz_hour), _tz_minute
		);
	return buffer;
}